In the course of automation in the field of sewing installations, automatic winding means have been developed which perform an automatic winding of lower-thread bobbins in sewing machines. However, in order to be efficient the automatic winding of bobbins requires also an automatic bobbin exchange.
Such an automatic bobbin exchange is described in U.S. Pat. No. 3 376 838. This purpose is served by a pneumatically swingable and electromagnetically displaceable gripper lever for the pickup of the bobbin from the bobbin case carrier of the sewing machine, while a carriage-like bobbin carrier can travel back and forth between the magazine and the sewing station.
A control unit monitors the timing of the operation of individual components. The device is comparatively obstructing and projects very far laterally, so that it is difficult to mount on the sewing machine.
U.S. Pat. No. 2 690 725 also shows an automatic bobbin changer, wherein a control shaft travelling back and forth is actuated by a pneumatic cylinder and has at its end a gripper claw carrier. The latter is pivotable about the axis of the control shaft and is provided with receiving devices for the pickup of the bobbins.
The transfer of the full or the empty bobbins takes place due to the rotation of the gripper claw carrier. The device has numerous complicated components and is expensive.